docs: def get_text(self, instance):
          """
          Haystack facets are returned as a two-tuple (value, count).
          The text field should contain the faceted value.
          """
          instance = instance[0]
          if isinstance(instance, (six.text_type, six.string_types)):
              return serializers.CharField(read_only=True).to_representation(instance)
          elif isinstance(instance, datetime):
              return serializers.DateTimeField(read_only=True).to_representation(instance)
          return instance